Breeding in southeastern Siberia, northeastern China, and possibly Mongolia and North Korea, these ducks winter in southern and eastern China and parts of South and Southeast Asia. Their diet is made up of aquatic insects, mollusks, shrimp, fish, and algae. Accomplished divers, they can spend about 40 seconds underwater and can reach depths of six and a half feet (2 meters) when searching for food. They often build their nests near those of their own and other species. The female incubates the eggs alone while the male guards her and brings food for her and the ducklings. Females sometimes lay their eggs in the nests of other ducks. They are listed as Critically Endangered by the IUCN, primarily due to habitat loss from rice farming and recently due to harvesting of their small population.